The term "Rule of Law" was popularized by A.V. Dicey, a British jurist and constitutional theorist. Dicey formulated the modern concept of the Rule of Law, emphasizing the importance of the supremacy of law over arbitrary power, the equality of all individuals before the law, and the protection of individual rights.
Though Salmond, Thomas, and Bentham have also contributed to legal theories, it was A.V. Dicey who truly defined the Rule of Law in the British legal system.
Thus, the correct answer is A.V. Dicey.